/*
 * Copyright 2015 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
#ifndef SkBmpCodec_DEFINED
#define SkBmpCodec_DEFINED

#include "include/codec/SkCodec.h"
#include "include/codec/SkEncodedImageFormat.h"
#include "include/core/SkColorType.h"
#include "include/core/SkTypes.h"
#include "modules/skcms/skcms.h"

#include <cstddef>
#include <cstdint>
#include <memory>

class SkStream;
struct SkEncodedInfo;
struct SkImageInfo;

/*
 * This class enables code sharing between its bmp codec subclasses.  The
 * subclasses actually do the work.
 */
class SkBmpCodec : public SkCodec {
public:
    static bool IsBmp(const void *, size_t);

    /*
     * Assumes IsBmp was called and returned true
     * Creates a bmp decoder
     * Reads enough of the stream to determine the image format
     */
    static std::unique_ptr<SkCodec> MakeFromStream(std::unique_ptr<SkStream>, Result *);

    /*
     * Creates a bmp decoder for a bmp embedded in ico
     * Reads enough of the stream to determine the image format
     */
    static std::unique_ptr<SkCodec> MakeFromIco(std::unique_ptr<SkStream>, Result *);

protected:
    SkBmpCodec(SkEncodedInfo &&info, std::unique_ptr<SkStream>, uint16_t bitsPerPixel,
        SkCodec::SkScanlineOrder rowOrder);

    SkEncodedImageFormat onGetEncodedFormat() const override
    {
        return SkEncodedImageFormat::kBMP;
    }

    /*
     * Read enough of the stream to initialize the SkBmpCodec.
     * On kSuccess, if codecOut is not nullptr, it will be set to a new SkBmpCodec.
     */
    static Result ReadHeader(SkStream *, bool inIco, std::unique_ptr<SkCodec> *codecOut);

    bool onRewind() override;

    /*
     * Returns whether this BMP is part of an ICO image.
     */
    bool inIco() const
    {
        return this->onInIco();
    }

    virtual bool onInIco() const
    {
        return false;
    }

    /*
     * Get the destination row number corresponding to the encoded row number.
     * For kTopDown, we simply return y, but for kBottomUp, the rows will be
     * decoded in reverse order.
     *
     * @param y      Iterates from 0 to height, indicating the current row.
     * @param height The height of the current subset of the image that we are
     * decoding.  This is generally equal to the full height
     * when we want to decode the full or one when we are
     * sampling.
     */
    int32_t getDstRow(int32_t y, int32_t height) const;

    /*
     * Accessors used by subclasses
     */
    uint16_t bitsPerPixel() const
    {
        return fBitsPerPixel;
    }
    SkScanlineOrder onGetScanlineOrder() const override
    {
        return fRowOrder;
    }
    size_t srcRowBytes() const
    {
        return fSrcRowBytes;
    }

    /*
     * To be overriden by bmp subclasses, which provide unique implementations.
     * Performs subclass specific setup.
     *
     * @param dstInfo         Contains output information.  Height specifies
     * the total number of rows that will be decoded.
     * @param options         Additonal options to pass to the decoder.
     */
    virtual SkCodec::Result onPrepareToDecode(const SkImageInfo &dstInfo, const SkCodec::Options &options) = 0;
    SkCodec::Result prepareToDecode(const SkImageInfo &dstInfo, const SkCodec::Options &options);

    uint32_t *xformBuffer() const
    {
        return fXformBuffer.get();
    }
    void resetXformBuffer(int count)
    {
        fXformBuffer.reset(new uint32_t[count]);
    }

    /*
     * BMPs are typically encoded as BGRA/BGR so this is a more efficient choice
     * than RGBA.
     */
    inline static constexpr SkColorType kXformSrcColorType = kBGRA_8888_SkColorType;
    inline static constexpr auto kXformSrcColorFormat = skcms_PixelFormat_BGRA_8888;

private:
    /*
     * Creates a bmp decoder
     * Reads enough of the stream to determine the image format
     */
    static std::unique_ptr<SkCodec> MakeFromStream(std::unique_ptr<SkStream>, Result *, bool inIco);

    /*
     * Decodes the next dstInfo.height() lines.
     *
     * onGetPixels() uses this for full image decodes.
     * SkScaledCodec::onGetPixels() uses the scanline decoder to call this with
     * dstInfo.height() = 1, in order to implement sampling.
     * A potential future use is to allow the caller to decode a subset of the
     * lines in the image.
     *
     * @param dstInfo     Contains output information.  Height specifies the
     * number of rows to decode at this time.
     * @param dst         Memory location to store output pixels
     * @param dstRowBytes Bytes in a row of the destination
     * @return            Number of rows successfully decoded
     */
    virtual int decodeRows(const SkImageInfo &dstInfo, void *dst, size_t dstRowBytes, const Options &opts) = 0;

    virtual bool skipRows(int count);

    Result onStartScanlineDecode(const SkImageInfo &dstInfo, const SkCodec::Options &) override;

    int onGetScanlines(void *dst, int count, size_t rowBytes) override;

    bool onSkipScanlines(int count) override;

    const uint16_t fBitsPerPixel;
    const SkScanlineOrder fRowOrder;
    const size_t fSrcRowBytes;
    std::unique_ptr<uint32_t[]> fXformBuffer;

    using INHERITED = SkCodec;
};

#endif
